Stone with emerald cut crown and modified brilliant cut base

ABSTRACT

A diamond is cut to emerald shape with the conventional crown breaks and girdle. The base of the diamond is formed to pyramidal shape, the pyramid forming about 41* with the girdle plane. Adjacent the girdle base breaks are made at between 52* and 65* to the girdle plane. Between these breaks and the collet pairs of halves are formed with the result that the base breaks acquire a half-moon shape or become lunulae. At the short sides of the emerald cut shape point corners are cut to extend to the apices of the halves. The crux of the matter resides in the base breaks that become lunulae.

United States Patent Watermeyer STONE WITH EMERALD CUT CROWN AND MODIFIED BRILLIANT CUT BASE [75] lnventor: Basil Watermeyer, Johannesburg,

South Africa [73] Assignee: Joostes Diamond Cutting Works (Proprietary) Limited, Johannesburg, South Africa [22] Filed: Nov. 15, 1971 [21] Appl. No.: 198,615

[30] Foreign Application Priority Data Feb. 1, 1970 South Africa 70/8135 [52] US. Cl. 63/32 [51] Int. Cl.'. A44c 17/00 p [58] Field of Search 63/32; 51/283; D45/l, 2

[5 6] References Cited UNITED STATES PATENTS 2,009,390 7/1935 Bayardi 63/32 3,286,486 11/1966 Huisman et al 63/32 OTHER PUBLlCATlONS Webster et al., Introductory Gemology, Pub. by Gem- Mar. 12, 1974 ological Institute of America (1945), Los Angeles, pp. 130-131 relied on.

Dieulafait, Diamonds & Precious Stones, Pub. by Scribner, Armstrong & C0., 1876, p. 93 relied on.

Primary ExaminerF. Barry Shay Attorney, Agent, or Firm-Young & Thompson [57] ABSTRACT A diamond is cut to emerald shape with the conventional crown breaks and girdle. The base of the diamond is formed to pyramidal shape, the pyramid forming about 41 with the girdle plane. Adjacent the girdle base breaks are made at between 52 and 65 to the girdle plane. Between these breaks and the collet pairs of halves are formed with the result that the base breaks acquire a half-moon shape or become lunulae. At the short sides of the emerald cut shape point corners are cut to extend to the apices of the halves. The

crux of the matter resides in the base breaks that become lunulae.

5 Claims, 5 Drawing Figures STONE WITH EMERALD CUT CROWN AND MODIFIED BRILLIANT CUT BASE This invention relates to a new diamond cut. The large majority of diamonds that are cut to-day are cut in a way which is known as the brilliant-cut. This is so because the brilliant-cut of all cuts known up to now most strikingly reveals the splendid fire of a diamond.

However, in many types of jewelry the brilliant-cut is not aesthetically acceptable. For these reasons designers often still call for a square-cut.

One major advantage which the square-cut has over the brilliant-cut is that the former results in a smaller loss of diamond. With a brilliant-cut the retention of diamond seldom exceeds 50 percent while with a square-cut the retention can be as high as 70 percent. Thus starting from the same raw stone the square-cut offers the diamond cutterless loss of raw material than the brilliant-cut. This has obvious economic advan-- tages.

But the brilliant-cut is still the cut of preference because of its desirability to the buying public.

One way in which a diamond is cut square is to form the crown as with an emerald-cut and forming the base with a square emerald-cut. In the latter case there are 25 to 58 full cut facets. However, there is still such a loss of fire, as compared with the brilliant-cut, that. this method is restricted to stones of a quarter carat or less. An object of-the invention is to provide a cut for diamonds which is adapted to give much more fire than coventional cuts when applied to a square cutdiamond.

' The cut of the invention is applicable to a diamond which viewed normal to the table is triangular, square rectangular or multisided in outline while the crown is cut emerald-cut fashion.

The present invention provides a cut diamond having a girle with at least three long sides and an equal number of short sides at the intersections of the long sides so cut as to provide a table, crown breaks of the emerald-cut type and a base which is substantially pyramidal in shape and formed with a collet characterized in that the base has: i

a lunula bordering each long side of the girdle and I corresponding to the first base break of an emerald cut,

a point corner extending from each short side along the ridges of the base pyramid,

two halves to each side of each point corner, and

a pavilion penetrating'between each pair of halves and having an apex at the boundary of a lunula.

The pavilion is a residual pyramidal facet of the original pyramidal base. The breaks on which the lunulae are formed preferably extend to about a quarter of the depth of the base. The pyramid may for an angle of about 41 with the girdle and the halves may be formed at the same inclination so that the point corners and the halves along a ridge have a common apex point spaced from the collet. The pavilions are thus of distorted lozenge shape having long points extending between halves and short truncated points extending from the collet. For best results the lunulae should be formed at angles between 52 and 65 to the plane of the girdle.

The invention also provides a cut diamond in which the lunulae are formed on breaks which extend about a quarter of the depth of the base.

The invention is further discussed with reference to the accompanying drawings, in which FIG. 1 is a pictorial view of a stone cut according to the invention,

FIG. 2 is an end view showing an early stage in the cutting of a diamond,

FIG. 3 shows a later stage,

FIG. 4 still alater stage, and

FIG. 5 is a plan view of a stone showing the reflection of the base as seen through the table.

A diamond out according to the invention has the following conventional features a table 6,- crown breaks 7,8 and 9, a collet 10 (shown exaggerated) at the tip of a substantially pyramid shaped base, and a girdle having long facets 11 and short or corner facets 12. The breaks, of course, also exist on the corners, but these have not been separately numbered.

After being cut and polished according'to the invention the stone has four lunulae 13, eight outer halves 14 and eight inner halves 15, four point corners 16 and four pavilions l7. Assuming that the crown has been cut and the girdle formed in the early stages of forming the base break 20 (FIG. 2) is formed at an angle of about 65 to the plane of the girdle while the remainder of the base is formed to pyramidal shape at an angle of about 41 /2 to the same plane. Working from a ridge of the pyramid each face of the pyramid is formed to provide two halves 21. Each half 21 is then further subdivided to provide outer and inner halves l4 and 15, the

former being residue of the original half 21. Pavilions 17 areleft.

Finally the point corners 16 are cut from the corner facets 12 and a collet is put on.

The procedure outlined above is given merely by way of example. Other sequences leading to the same final result may be used. Thus some may prefer to form the point corners 16 prior to forming the halves.

A variety of diamonds, of different sizes, have been square cut according to the invention. Especially in the smaller sizes the fire apparent to the observer approaches that of the brilliant-cut. Those stones that have been supplied to the trade have met with very favourable comment especially in markets where square-cuts are preferred.

Obviously the principles explained in the above embodiment may be applied to other straightsided shapes of diamonds such as triangular and rectangular shapes. Indeed where a stone warrants emerald type breaks on the crown, the principles of the invention may be applied to stones which at the girdle will have more than four sides. The applicant believes, however, that the base should be such as to provide lunulae which form an angle of between 52 and 65 with the plane of the girdle. In all these cases a prime object of utilising the cut of the invention will be to retain as much as possible of the valuable diamond substance.

I claim: 1

1. A cut diamond having a girdle with at least three I long straight sides and an equal number of short sides at the intersections of the long sides so cut as to provide a table, crown breaks of the emerald-cut type and a base vwhich is substantially pyramidal in shape and formed with a collet, characterized in that the base has: a lunula bordering each said long side along substantially the entire length thereof and corresponding to the first base break of an emerald cut, a point corner extending from each short side along the ridges of the base pyramid, two halves to each side of each point corner, and a pavilion penetrating between each pair of halves and having an apex at the boundary of a lunula,

4. A cut diamond claimed in claim 3 in which the residual pyramidical faces form an angle of about 41 with the girdle and the halves are formed at the same inclination, so that the pavilions and the halves along a ridge have a common apex point spaced from the collet.

5. A cut diamond as claimed in claim 3 in which the girdle has four long sides of equal length to constitute a square cut diamond. 

1. A cut diamond having a girdle with at least three long straight sides and an equal number of short sides at the intersections of the long sides so cut as to provide a table, crown breaks of the emerald-cut type and a base which is substantially pyramidal in shape and formed with a collet, characterized in that the base has: a lunula bordering each said long side along substantially the entire length thereof and corresponding to the first base break of an emerald cut, a point corner extending from each short siDe along the ridges of the base pyramid, two halves to each side of each point corner, and a pavilion penetrating between each pair of halves and having an apex at the boundary of a lunula, each of said halves having a side defined by a side of one of said lunulae and each said pair of halves being bounded by a side of one of said point corners and one of said pavilions.
 2. A cut diamond as claimed in claim 1 in which the lunulae are formed on breaks which extend about a quarter of the depth of the base.
 3. A cut diamond as claimed in claim 2 in which the lunulae are formed at angles between 52* and 65* to the plane of the girdle.
 4. A cut diamond claimed in claim 3 in which the residual pyramidical faces form an angle of about 41* with the girdle and the halves are formed at the same inclination, so that the pavilions and the halves along a ridge have a common apex point spaced from the collet.
 5. A cut diamond as claimed in claim 3 in which the girdle has four long sides of equal length to constitute a square cut diamond. 